1. Field
The embodiments relate to an organic light emitting diode (OLED) display device and a method of driving the same, and more particularly, to an OLED display device that is capable of preventing characteristics of an amorphous silicon thin film transistor from being degraded and deteriorated and a method of driving the same.
2. Description of the Related Art
In general, an OLED display device includes a display panel configured to display an image, and a drive circuit configured to drive the display panel. The display panel includes an OLED formed between two substrates, and at least one thin film transistor (TFT) configured to drive the OLED.
The OLED includes an anode electrode, a cathode electrode, and an emission layer disposed between the anode electrode and the cathode electrode.
An electron injected from the cathode electrode is coupled to a hole injected from the anode electrode to form an exciton in the emission layer, and the exciton emits energy to emit light.
The TFTs may include a switching TFT configured to select a pixel, and a drive TFT configured to drive the OLED to emit light having brightness in proportion to a current.
Here, as the TFT, an amorphous silicon TFT or a polysilicon TFT may be selected considering image quality, power consumption, stability, a large-sized screen, costs, etc.
When the conventional amorphous TFT is driven for a long time, characteristics of the amorphous silicon TFT may be deteriorated. Consequently, a threshold voltage Vth may increase, and mobility of the amorphous silicon TFT may decrease.
Such a phenomenon occurs because a dangling bond is formed in an amorphous silicon thin film. The dangling bond may cause more defects in the thin film and increase in a trap density at an interface between amorphous silicon and gate oxide, and decrease in mobility of a charge.
In addition, the current required to drive the OLED is varied to generate a difference in screen display characteristics according to a unit pixel in the panel. Therefore, when characteristics of the drive TFT are changed due to degradation or deterioration of the TFT, reliability of products may be decreased.